title: Full-range k-domain linearization in spectral-domain optical coherence tomography.
abstract: A full-bandwidth k-domain linearization method for spectral-domain optical coherence tomography (SD-OCT) is demonstrated. The method uses information of the wavenumber-pixel-position provided by a translating-slit-based wavelength filter. For calibration purposes, the filter is placed either after a broadband source or at the end of the sample path, and the filtered spectrum with a narrowed line width (∼0.5 nm) is incident on a line-scan camera in the detection path. The wavelength-swept spectra are co-registered with the pixel positions according to their central wavelengths, which can be automatically measured with an optical spectrum analyzer. For imaging, the method does not require a filter or a software recalibration algorithm; it simply resamples the OCT signal from the detector array without employing rescaling or interpolation methods. The accuracy of k-linearization is maximized by increasing the k-linearization order, which is known to be a crucial parameter for maintaining a narrow point-spread function (PSF) width at increasing depths. The broadening effect is studied by changing the k-linearization order by undersampling to search for the optimal value. The system provides more position information, surpassing the optimum without compromising the imaging speed. The proposed full-range k-domain linearization method can be applied to SD-OCT systems to simplify their hardware/software, increase their speed, and improve the axial image resolution. The experimentally measured width of PSF in air has an FWHM of 8 μm at the edge of the axial measurement range. At an imaging depth of 2.5 mm, the sensitivity of the full-range calibration case drops less than 10 dB compared with the uncompensated case.
authors.affiliation: School of Electrical Engineering and Computer Science, Kyungpook National University, Sankyuk-dong, Buk-gu, Daegu, South Korea.
authors.forename: Mansik
authors.initials: M
authors.lastname: Jeon
authors.forename: Jeehyun
authors.initials: J
authors.lastname: Kim
authors.forename: Unsang
authors.initials: U
authors.lastname: Jung
authors.forename: Changho
authors.initials: C
authors.lastname: Lee
authors.forename: Woonggyu
authors.initials: W
authors.lastname: Jung
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Boppart
mesh_terms: D000465:Algorithms; D002138:Calibration; D003315:Cornea / Q000648:ultrastructure; D004867:Equipment Design; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation; D012160:Retina / Q000648:ultrastructure; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis / Q000295:instrumentation*; D041623:Tomography, Optical Coherence / Q000295:instrumentation / Q000379:methods